Patent Application
20120206222
1. Field of the Invention
The disclosed invention generally relates to an electromagnetic relay assembly incorporating a rotatable coil-core assembly. More particularly, the disclosed invention relates to an electromagnetic relay assembly having a magnetically actuable coil assembly rotatable about an axis of rotation extending orthogonally relative to the coil assembly axis.
2. Brief Description of the Prior Art
Generally, the function of an electromagnetic relay is to use a small amount of power in the electromagnet to move an armature that is able to switch a much larger amount of power. By way of example, the relay designer may want the electromagnet to energize using 5 volts and 50 milliamps (250 milliwatts), while the armature can support 120 volts at 2 amps (240 watts). Relays are quite common in home appliances where there is an electronic control turning on (or off) some application device such as a motor or a light. Several exemplary electromagnetic relay assemblies reflective of the state of the art and disclosed in United States patents are briefly described hereinafter.
U.S. Pat. No. 6,046,660 ('660 patent), which issued to Gruner, discloses a Latching Magnetic Relay assembly with a Linear Motor. The '660 patent describes a latching magnetic relay capable of transferring currents of greater than 100 amps for use in regulating the transfer of electricity or in other applications requiring the switching of currents of greater than 100 amps. A relay motor assembly has an elongated coil bobbin with an axially extending cavity therein. An excitation coil is wound around the bobbin. A generally U shaped ferromagnetic frame has a core section disposed in and extending through the axially extending cavity in the elongated coil bobbin.
Two contact sections extend generally perpendicularly to the core section and rises above the motor assembly. An actuator assembly is magnetically coupled to the relay motor assembly. The actuator assembly is comprised of an actuator frame operatively coupled to a first and a second generally U-shaped ferromagnetic pole pieces, and a permanent magnet. A contact bridge made of a sheet of conductive material copper is operatively coupled to the actuator assembly.
U.S. Pat. No. 6,246,306 ('306 patent), which issued to Gruner, discloses an Electromagnetic Relay with Pressure Spring. The '306 patent teaches an electromagnetic relay having a motor assembly with a bobbin secured to a housing. A core is adjacently connected below the bobbin except for a core end, which extends from the bobbin. An armature end magnetically engages the core end when the coil is energized. An actuator engages the armature and a plurality of center contact spring assemblies. The center contact spring assembly is comprised of a center contact spring which is not pre bent and is ultrasonically welded onto a center contact terminal.
A normally open spring is positioned relatively parallel to a center contact spring. The normally open spring is ultrasonically welded onto a normally open terminal to form a normally open outer contact spring assembly. A normally closed outer contact spring is vertically positioned with respect to the center contact spring so that the normally closed outer contact spring assembly is in contact with the center contact spring assembly, when the center contact spring is not being acted upon by the actuator. The normally closed spring is ultrasonically welded onto a normally closed terminal to form a normally closed assembly. A pressure spring pressures the center contact spring above the actuator when the actuator is not in use.
U.S. Pat. No. 6,252,478 ('478 patent), which issued to Gruner, discloses an Electromagnetic Relay. The '478 patent describes an electromagnetic relay having a motor assembly with a bobbin secured to a frame. A core is disposed within the bobbin except for a core end which extends from the bobbin. An armature end magnetically engages the core end when the coil is energized. An actuator engages the armature and a plurality of movable blade assemblies. The movable blade assembly is comprised of a movable blade ultrasonically welded onto a center contact terminal.
A normally open blade is positioned relatively parallel to a movable blade. The normally open blade is ultrasonically welded onto a normally open terminal to form a normally open contact assembly. A normally closed contact assembly comprised of a third contact rivet and a normally closed terminal. A normally closed contact assembly is vertically positioned with respect to the movable blade so that the normally closed contact assembly is in contact with the movable blade assembly when the movable blade is not being acted upon by the actuator.
U.S. Pat. No. 6,320,485 ('485 patent), which issued to Gruner, discloses an Electromagnetic Relay Assembly with a Linear Motor. The '485 patent describes an electromagnetic relay capable of transferring currents of greater than 100 amps for use in regulating the transfer of electricity or in other applications requiring the switching of currents of greater than 100 amps. A relay motor assembly has an elongated coil bobbin with an axially extending cavity therein. An excitation coil is wound around the bobbin. A generally U shaped ferromagnetic frame has a core section disposed in and extending through the axially extending cavity in the elongated coil bobbin.
Two contact sections extend generally perpendicularly to the core section and rises above the motor assembly. An actuator assembly is magnetically coupled to the relay motor assembly. The actuator assembly is comprised of an actuator frame operatively coupled to a first and a second generally U-shaped ferromagnetic pole pieces, and a permanent magnet. A contact bridge made of a sheet of conductive material copper is operatively coupled to the actuator assembly.
U.S. Pat. No. 6,563,409 ('409 patent), which issued to Gruner, discloses a Latching Magnetic Relay Assembly. The '409 patent describes a latching magnetic relay assembly comprising a relay motor with a first coil bobbin having a first excitation coil wound therearound and a second coil bobbin having a second excitation coil wound therearound, both said first excitation coil and said second excitation coil being identical, said first excitation coil being electrically insulated from said second excitation coil; an actuator assembly magnetically coupled to both said relay motor, said actuator assembly having a first end and a second end; and one or two groups of contact bridge assemblies, each of said group of contact bridge assemblies comprising a contact bridge and a spring.
Other patent disclosures of particular interest are U.S. Pat. No. 4,743,877, which issued to Oberndorfer et al.; U.S. Pat. No. 5,568,108, which issued to Kirsch; U.S. Pat. Nos. 5,910,759; 5,994,987; 6,020,801; 6,025,766, all of which issued to Passow; U.S. Pat. No. 5,933,065, which issued to Duchemin; U.S. Pat. No. 6,046,661, which issued to Reger et al.; U.S. Pat. No. 6,292,075, which issued to Connell et al.; U.S. Pat. No. 6,426,689, which issued to Nakagawa et al.; U.S. Pat. Nos. 6,661,319 and 6,788,176, which issued to Schmelz; U.S. Pat. No. 6,949,997, which issued to Bergh et al.; U.S. Pat. No. 6,940,375, which issued to Sanada et al.; and U.S. Patent Application Publication No. 2006/0279384, which was authored by Takayama et al.
The Schmelz, Duchemin, and certain of the Gruner disclosures were particularly relevant to the subject matter as described in U.S. Pat. No. 7,659,800 (the '800 patent) and U.S. Pat. No. 7,710,224 (the '224 patent), which issued to Gruner et al. The '800 and '224 patents describe electromagnetic relays essentially comprising a coil assembly, a rotor or bridge assembly, and a switch assembly. The coil assembly comprises a coil and a C-shaped core. The coil is wound round a coil axis extending through the core. The core comprises core termini parallel to the coil axis. The bridge assembly comprises a H-shaped bridge and an actuator.
The bridge comprises medial, lateral, and transverse field pathways. The actuator extends laterally from the lateral field pathway. The core termini are coplanar with the axis of rotation and received intermediate the medial and lateral field pathways. The actuator is cooperable with the switch assembly. The coil creates a magnetic field directable through the bridge assembly via the core termini for imparting bridge rotation about the axis of rotation. The bridge rotation displaces the actuator for opening and closing the switch assembly.
Notably, the Kirsch U.S. Pat. No. 5,568,108; the Reger et al. U.S. Pat. No. 6,046,661; the Nakagawa et al. U.S. Pat. No. 6,426,689; the Schmelz U.S. Pat. Nos. 6,661,319 and 6,788,176 and the Gruner et al. '800 and 224 patents teach or describe armature assemblies having an H-shaped portion pivotable about a pivot axis of rotation, which H-shaped portion comprises or is otherwise attached to an elongated actuator arm extending from the H-shaped portion.
It is noted that an inherent problem with conventional electromagnetic relays incorporating a coil assembly and an armature of the foregoing type(s) is that they are quite susceptible to magnetic tampering. This is primarily because the rotating armature houses a permanent magnet. These permanent magnets react to the magnetic field generated by the coil and are either repelled or attracted, thereby creating a mechanical motion to open and/or close the contacts. This leaves the relay(s) vulnerable to tampering by using a very large magnet (i.e.
positioning a large conflicting magnetic field) external to the relay. Since the permanent magnets are housed in a rotating plastic casing, this means t will only hold its state as long as no other magnetic or mechanical force is exerted to the relay which is larger than the magnetic holding force of the permanent magnets.
It is noted that certain international standards require that the relay hold its state in either the open or closed position when a magnetic field measuring at least 5000 Gauss is brought within 40 millimeters of the relay. During this test, many relays cannot operate due to the conflicting 5000 Gauss magnetic field. This type of tampering is common in developing countries or in lower income areas to turn the electricity meter back on after the utility company has remotely shut it off.
The prior art thus perceives a need for an electromagnetic relay that is resistant to magnetic tampering whereby the permanent magnets are fixed or anchored and the coil assembly itself rotates with minimized displacements so as to intensify the operative magnetic field otherwise inherent to the same size magnets.
It is thus on object of the present invention to provide a so-called bi-stable electromagnetic relay assembly in which the permanent magnets are fixed inside the plastics and the coil itself rotates, unlike conventional relays incorporating fixed coils and moving permanent magnets cooperably associated with rotating armatures. To achieve this and other readily apparent objectives, the present invention essentially provides an electromagnetic relay assembly for selectively enabling current to pass through switch termini, which relay comprises a rotatable electromagnetic coil assembly, first and second pairs of opposed permanent magnets, and a switch assembly.
The rotatable coil assembly comprises a current-conductive coil, an axially extending coil core, and a rotatable coil housing. The coil is wound around the core, which core is collinear or parallel with the axis of the coil. The coil comprises electromagnet-driving termini, the core comprises opposed core termini, and the coil housing has a housing axis of rotation orthogonal to the coil axis.
The first and second pairs of opposed permanent magnets are respectively and fixedly positioned adjacent the core termini such that the core termini are respectively displacable intermediate the pairs of magnets. The switch assembly comprises first and second linkage arms, and first and second spring arms. The linkage arms interconnect the core termini and spring arms. The spring arms each comprise opposed pairs of contacts and a switch terminal.
The coil operates to create a magnetic field directable through the core for imparting coil housing rotation about the housing axis of rotation via attraction to the positioned/anchored permanent magnets. The core termini displace linkage arms, and the linkage arms actuate the spring arms intermediate an open switch assembly position and a closed switch assembly position, the latter of which enables current to pass through the switch assembly via the contacts and the switch termini.
Certain peripheral features of the essential electromagnetic relay assembly include, for example, certain spring means for damping contact vibration intermediate the contacts when switching from the open position to the closed position. In this regard, it is contemplated that the spring arms each may preferably comprise first and second spaced spring sections cooperable with the linkage arms and laterally spaced from the contacts so as to maximize the damping effect when switching from the open to closed switch assembly positions.
In this last regard, it is noted that a major problem for all electro-mechanical switchgear is the contact bounce when closing into an electric load. To overcome this, many have added additional leaf or coil springs to buffer the bounce of the contacts. The present invention takes advantage of a simple stamping process which enables the incorporation of an integrated bounce reduction spring on both sides of the contact site rather than just one.
While the loose end of a spring is the most likely place to open when operating the relay, it can still occur that the contacts open even if the loose end of the spring is set to the closed position. To overcome this, an additional stamping procedure has been incorporated into the present invention so as to apply contact pressure both the left and right side of the contact, ensuring equal contact pressure and making sure that the contacts stay closed when the relay is operated. Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated or become apparent from, the following description and the accompanying drawing figures.
Other features of my invention will become more evident from a consideration of the following brief description of patent drawings:
Referring now to the drawings, the preferred embodiment of the present invention concerns a so-called bi-stable electromagnetic relay (with X-drive motor) assembly 10 as generally illustrated and referenced in
The electromagnetic relay assembly 10 essentially functions to selectively enable current to pass through switch termini 11. The electromagnetic relay assembly 10 preferably comprises an electromagnetic coil assembly 12, first and second pairs of opposed permanent magnets 13, and a switch assembly comprising various components, including first and second linkage arms 14 (comprising one or more L-shaped portion(s)), and first and second spring arms 15, which arms 15 are in electrical communication with, or otherwise (conductively) fastened extensions of the switch termini 11.
The coil assembly 12 may preferably be thought to comprise a current-conductive coil 16 (with spool assembly 26), a coil core 17, and a coil housing 18 (comprising a coil lid 18(a) (outfitted with coil lid conductor(s) 25) and a coil base or coil box 18(b)). The coil 16 is wound around the core 17, which core 17 is collinear with a coil axis as at 100. The coil 16 comprises electromagnet-driving termini as at 19, and the core 17 comprises (linearly) opposed core termini as at 21.
Notably, the coil housing 18 has a housing axis of rotation 101, which axis 101 extends orthogonally relative to the coil axis 100. The housing axis of rotation 101 extends through pin structures 22 formed in axial alignment on the coil lid 18(a) and the coil box 18(b) of the housing 18, which pin structures 22 are received in pin-receiving structures 23 formed in a bracket 27 and relay housing 24.
The first and second pairs of opposed permanent magnets 13 are respectively and fixedly obliquely positioned (via housing anchor structures 28) adjacent the core termini 21 such that the core termini 21 are respectively displacable intermediate the respective pairs of magnets 13. The opposed pairs of permanent magnets 13 each comprise substantially planar opposed magnet faces 29, which faces 29 extend in intersecting planes 102 thereby exhibiting an X-shaped planar configuration as at 103 in Figure No. generally defining the boundaries of movement of the core termini 21.
In this last regard, it will be noted that the core 17 has a thickness as at 104, and the magnets 13 are positioned (via anchor structures 28) accordingly so as to properly contact the core termini 21. In other words, the core 17 preferably comprises substantially planar opposed core faces as at 30 such that the core faces 30 and magnet faces 29 are similarly angled when contacting one another for maximizing contact surface area and enhancing current flow through the maximized contacting surface area intermediate the core 17 and permanent magnets 13.
It will be understood form a consideration of the drawings that the linkage arms 14 (or linkage arms 14(a) of the multi-pole embodiment) function to interconnect the core termini 21 and spring arms 15. The spring arms 15 each comprise (i.e. are in electrical communication with or otherwise conductively fastened to) opposed pairs of contacts 31 and a switch terminal as at 11. The opposed pairs of contacts 31 are juxtaposed adjacent one another such that when the switch assembly is in a closed position, the contacts 31 contact one another as generally depicted in
The coil 16, when provided with current, functions to create a magnetic field as at 105, which magnetic field 15 is directable through the core 17 and cooperable with the magnets 13 (as generally pole aligned and depicted in
As earlier noted the linkage arms of assembly 10 are preferably L-shaped from a top plan view and thus comprise a first link portion as at 32 and a second link portion as at 33. With assembly 20, the linkage arms 14 comprise a first link portion as at 34 and a series of second link portions as at 35 (or a series of interconnected L-shaped structures). The second link portions 33 and 35 of each assembly 10/20 respectively extend toward one another orthogonal to the first link portions 32 and 34 of each assembly 10/20. The core termini 21 are connected to the first link portions 32 or 34 and the spring arms 15 extend substantially parallel to the second link portions 33 or 35 when in an open switch assembly position.
The spring arms 15 are preferably parallel to one another whether in the open or closed switch assembly positions and each comprise opposed faces, the inner faces 40 of which face one another as generally depicted and referenced in
In this last regard, it is noted that during a short circuit the magnetic fields generated inside a relay will grow as the current increases. The contacts, however, tend to separate during the rush of current. To structurally address this, the present invention enables the manufacturer to form one type of contact-spring assembly, and use the same assembly twice as generally depicted and illustrated by spring arm(s) 15, termini 11, and contacts 31.
It should be noted that half the current will flow through the top contact-spring assembly and half the current will flow through the bottom contact-spring assembly. Since these assemblies are carrying the same current in the same direction, the magnetic forces generated thereby are therefore equal. This means that when the bottom of the top spring is generating a magnetic field with a south polarity, the top of the bottom spring will generate a magnetic field with a north polarity. Since north and south attract one another (as at 107), the attraction forces the contacts 31 into the closed position during a short circuit. The greater the current during the short circuit, the greater will be the magnetic field; therefore, the magnetic attraction 107 to maintain the contacts 31 in a closed position is maximized.
The described contact-spring assembly is similar to existing assemblies insofar as the terminals 11 and spring arms 15 are preferably constructed from copper whereby the spring arm 15 is placed on top of the copper terminal and then riveted together via the contact buttons 31. By arranging the spring arms 15 so that faces 40 oppose one another, a resulting contact system allows for one input from a copper terminal, then splits the load through two springs and outputs the load again on the other copper terminal. Since the two springs (i.e. spring arms 15) are preferably identical in terms of their manufacturability, they will bear a very similar, if not identical, resistance. Furthermore, these two springs are running directly parallel to one another, resulting in the same magnetic fields generated around the spring arms 15.
The spring arms 15 preferably comprise first and second spring portions or means for effecting bi-stability. The first spring portions or means are generally contemplated to be exemplified by resiliently bends in the arms 15 as generally depicted and referenced at 36. The first spring means are preferably relaxed when in an open switch assembly position and preferably actuated when in a closed switch assembly position, but not necessarily so. It is contemplated that the actuated first spring means may well function to dampen contact vibration intermediate the contacts 31 when switching from the open switch assembly position to the closed switch assembly position.
The second spring portions or means are generally contemplated to be exemplified by resilient spring extensions as generally depicted and referenced at 37. The second spring portions or means 37 are preferably relaxed when in an open switch assembly position and preferably actuated when in a closed switch assembly position, but not necessarily so configured. It is contemplated that the actuated second spring means may well function to enhance damped contact vibration intermediate the contacts 31 when switching from the open switch assembly position to the closed switch assembly position.
It should be noted that first spring means are preferably actuable adjacent the first link portions 32 or 34 and that the second spring means are preferably actuable adjacent the second link portions 33 or 35. The first and second spring means thus provide spaced damping means for each contact pair. It is contemplated that the spaced damping means may well function to further enhance damped contact vibration intermediate the contacts 31 when switching from the open switch assembly position to the closed switch assembly position.
In this last regard, it should be further noted that each contact pair is preferably positioned intermediate the spaced first and second damping means, which spaced damping means thus provide laterally opposed damping means relative to each contact pair for still further enhancing damped contact vibration intermediate the contacts 31 when switching from the open switch assembly position to the closed switch assembly position.
As earlier noted, a major problem for all electro-mechanical switchgear is the contact bounce when closing into an electric load. To overcome this, the typical structural remedy is to include additional leaf or coil springs to buffer the bounce of the contacts. The present invention takes advantage of a simple stamping process which enables the incorporation of an integrated bounce reduction spring as exemplified by resilient bends 36 and resilient extensions 37, which structural features are spaced laterally relative to the contacts 31. The present design thus applies contact pressure both the left and right side of the contact, ensuring equal contact pressure and making sure that the contacts stay closed when the relay is operated.
While the above descriptions contain much specificity, this specificity should not be construed as limitations on the scope of the invention, but rather as an exemplification of the invention. For example, the invention may be said to essentially teach or disclose an electromagnetic relay assembly comprising a rotatable coil assembly, opposed pairs of attractive magnets, and a switch assembly.
The coil assembly comprises a coil, a core, and certain core-rotating means as exemplified by the rotatable coil housing with peripheral, pivot type rotation-enabling structures. The core is preferably collinear with or parallel to the axis of the coil and comprises exposed and opposed core termini. Notably, the core-rotating means have an axis of rotation that extends orthogonally relative to the coil axis.
The opposed pairs of attractive magnets are respectively and fixedly positioned adjacent the core termini such that the core termini are respectively displacable intermediate the magnet pairs. The coil function to create a magnetic field directable through the core into opposed magnets for imparting rotation about the axis of rotation. The core termini actuate the switch assembly intermediate an open position and a closed position, the latter of which positions enable current to pass through the switch assembly.
The electromagnetic relay assemblies further comprise certain linkage means and opposed spring assemblies. The linkage means as exemplified by the linkage arms 14 and 14(a) interconnect the core termini and spring assemblies. The spring assemblies essentially function to dampen contact vibration when switching from the open position to the closed position. The spring assemblies preferably comprise first and second spring means, which means are preferably relaxed when in the open position and preferably actuated when in the closed position, but the reverse structural configuration, namely that the first and second spring means may be relaxed when in the closed position and actuated when in the open position are also viable alternatives.
The first and second spring means are spaced from one another opposite the contacts for providing spaced, laterally opposed damping means for further enhancing damped contact vibration of the switch assembly when switching from the open to closed positions. The spring arms of the spring assemblies are preferably parallel to one another and comprise opposed arm faces as at 40. The opposed arm faces 40 are magnetically attractive to one another during a short circuit scenario, which magnetically attractive arm faces for maintaining the switch assembly in the closed position during the short circuit scenario.
The attractive magnets comprise opposed magnet faces, which opposed magnet faces are substantially planar and extend in intersecting planes, and the core (termini) have substantially planar opposed core faces. The contacting core faces and magnet faces are similarly angled for maximizing contact surface area for further enhancing current flow through contacting surface area intermediate the core and magnet faces.
In addition to the foregoing structural considerations, it is further believed that the inventive concepts discussed support certain new methodologies and/or processes. In this regard, it is contemplated that the foregoing structure considerations support a method for switching an electromagnetic relay comprising the steps of outfitting a coil assembly with means for rotating the coil assembly about an axis of rotation orthogonal to coil assembly axis whereafter a magnetic field may be created via the coil assembly and directed through the coil assembly into opposed magnets for imparting rotation about the axis of rotation. The coil assembly is then rotated (or pivoted) about the axis of rotation, and the switch assembly is actuated intermediate open and closed positions via the rotating coil assembly.
The method is believed to further comprise the step of damping contact vibration via opposed contact-spring assemblies when displacing the switch assembly from the open to closed position, which may involve the step of laterally spacing the damping means relative to contacts of the switch assembly before the step of damping contact vibration. Certain faces (as at 40) of the contact-spring assemblies may be opposed before the step of damping contact vibration such that the opposed faces are magnetically attractive to one another during a short circuit scenario for maintaining the switch assembly in the closed position during said scenario.
Although the invention has been described by reference to a number of embodiments it is not intended that the novel device or relay be limited thereby, but that modifications thereof are intended to be included as falling within the broad scope and spirit of the foregoing disclosure and the appended drawings. For example, the foregoing specifications support an electromagnetic relay assembly primarily intended for use as a single pole relay assembly as at 10. It is contemplated, however, that the essence of the invention may be applied in multi-pole relay assemblies as generally depicted and referenced by assembly 20, having unique construction and functionality in their own right, but which are enabled by the teachings of the single pole embodiment primarily set forth in this disclosure.
